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Re: Question on vrp_meet in tree-vrp.c
- From: ja2morri at csclub dot uwaterloo dot ca (James A. Morrison)
- To: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- Cc: gcc at gcc dot gnu dot org
- Date: Tue, 06 Sep 2005 00:57:23 -0400
- Subject: Re: Question on vrp_meet in tree-vrp.c
- References: <10509052127.AA02439@vlsi1.ultra.nyu.edu>
kenner@vlsi1.ultra.nyu.edu (Richard Kenner) writes:
> [Sorry for the missing line in my last message.]
>
> I'm watching it deal with
>
> # small_1 = PHI <32(0), 1(1)>
>
> vrp_meet is called with [32, 32] and [1,1].
>
> It determines that the ranges don't intersect and then comes up with
> ~[0,0] since neither contain zero. But wouldn't [1,32] be a better
> result?
Yes, but this may require more thinking to ensure all the cases are correct.
So, probably not something that will be done for 4.1.
--
Thanks,
Jim
http://www.csclub.uwaterloo.ca/~ja2morri/
http://phython.blogspot.com
http://open.nit.ca/wiki/?page=jim